1. Field of the Invention
The invention relates to a stepper, more particularly to a stepper having pedal bodies that can be maintained in a substantially horizontal position when the stepper is in use.
2. Description of the Related Art
Referring to FIG. 1, a conventional stepper 10 is shown to comprise a base frame 11 with a handlebar assembly 110 mounted thereon, and a pair of pedal units (only one is shown) on two sides of the handlebar assembly 110. Each of the pedal units includes a swing arm 12 mounted pivotally on the base frame 11 at one end thereof and having a pedal body 13 mounted securely on the other end thereof. A magnet-type resistance unit 14 is mounted on the base frame 11. Each of a pair of tension springs 122 (only one is shown) has a first end connected to the handlebar assembly 110 and a second end connected to a respective one of the swing arms 12, thereby placing the swing arms 12 in normal upwardly inclining positions. Each of the swing arms 12 further has an intermediate section provided with a transverse shaft 120 for mounting rotatably a drive gear 121 thereon. First and second axles 150, 160 are journalled on the base frame 11, while a third axle 170 is mounted securely on the base frame 11. The first axle 150 has two gear wheels 151 (only one is shown) mounted thereon by means of unidirectional bearings (not shown). Each of two transmission chains 18 (only one is shown) is trained on one of the drive gears 121, one of the gear wheels 151 and on one of two gear wheels 17 (only one is shown) that are disposed rotatably on the third axle 170, and has a first end secured to the base frame 11 and a second end secured to the respective gear wheel 17. A first belt wheel 15 is mounted securely on the first axle 150 between the gear wheels 151. Second and third belt wheels 161, 16 are mounted securely on the second axle 160. A first endless drive belt 191 is trained between the first belt wheel 15 and the second belt wheel 161. A second endless drive belt 192 is trained between the third belt wheel 16 and a belt wheel 141 of the resistance unit 14. Two torsion springs 171 (only one is shown) are sleeved on the third axle 170 and serve to resist rotation of a corresponding one of the gear wheels 17 in a certain direction.
When pressure is applied on one of the pedal bodies 13, the corresponding swing arm 12 pivots downwardly, thereby stretching the corresponding tension spring 122. The drive gear 121 on the swing arm 12 pulls the corresponding transmission chain 18, thereby causing the corresponding gear wheels 151, 17 to rotate. At this stage, the first belt wheel 15 rotates to drive rotatably the second belt wheel 161 via the drive belt 191, and the third belt wheel 16 rotates to drive rotatably the belt wheel 141 of the resistance unit 14 via the drive belt 192. When the pressure on the pedal body 13 is released, the corresponding tension spring 122 contracts to cause upward pivoting movement of the corresponding swing arm 12. The torsion spring 171 associated with the corresponding gear wheel 17 causes the latter to rotate in an opposite direction to wind the corresponding transmission chain 18 thereon.
The drawbacks of the conventional stepper 10 are as follows:
1. Since the pedal bodies 13 are mounted securely on the swing arms 12, the pedal bodies 13 cannot be maintained in a substantially horizontal position when the conventional stepper 10 is in use. Thus, the conventional stepper 10 is not suitable for use by old people and by children since they may easily lose their balance when exercising on the conventional stepper 10.
2. In order to enable the resistance unit 14 to resist downward pivoting movement of the swing arms 12, two drive gears 121, two gear wheels 17, two transmission chains 18, and first, second and third belt wheels 15, 161, 16 are employed. Thus, the conventional stepper 10 is relatively complicated in construction and is relatively expensive due to the large number of components used in the connection between the resistance unit 14 and the swing arms 12.